U.S. Pat. No. 3,138,904 entitled “METHOD AND APPARATUS FOR TYING PACKAGES AND WRAPPING MATERIALS;” U.S. Pat. No. 3,059,670 entitled “WIRE TWISTING TOOL;” U.S. Pat. No. 3,919,829 entitled “APPARATUS FOR TYING PACKAGES AND WRAPPING MATERIALS;” U.S. Pat. No. 4,856,258 entitled “WIRE TYING DEVICE;” and U.S. Pat. No. 5,483,134 entitled “RIBBON SENSING DEVICE FOR BAG TYER” disclose apparatus used for closing a plastic bag by attaching and twisting a wire-like ribbon about the neck of the bag.
Bag tying devices of the type disclosed in the aforementioned patents are commercially available from Burford Corporation of Maysville, Okla. The tying devices are generally constructed to receive packages such as loaves of bread at speeds of for example over one hundred (100) packages per minute at speeds of about 108 feet per minute.
Plastic bags containing bakery products, paper plates and ice are easily opened by removing the twisted ribbon from about the neck of the bag so that the contents of the bag are accessible. The bag can be resealed by manually replacing and twisting the ribbon about the neck of the bag.
U.S. Pat. No. 5,600,938 discloses apparatus for sealing a plurality of spaced spots across the flattened open end of a filled plastic bag. The bag is moved along a conveyor past a sealing mechanism where a plurality of spaced spots are welded or fused across the open end of the bag. In one embodiment a sealing mechanism includes a plurality of heated pins which penetrate the two layers of the open end of the bag while the end of the bag is substantially flat. These pins then move along with the bag in synchronism with the conveyor while the fusing occurs. In another embodiment, the scaling is accomplished by using a wheel having heated pins around its periphery and the wheel is rotated so that its tangential speed is in synchronism with the conveyor to successively make spaced fused spots across the generally flat open end of the bag. The apparatus seals a plurality of spaced spots to only delicately seal the bag to show evidence of tampering by breaking the seal but allow the bag to be opened without tearing or destroying the bag.
U.S. Pat. No. 5,741,075 describes a package comprising a flexible plastic bag and a label, the bag having a closed end, the closed end being openable to provide an opening for access to the contents of the package, wherein, the closed end of the package is initially sealed at a scaling area and, wherein, the sealing area is provided with a line of perforations to define the opening and reclosable by means of the label. The label is disclosed as having on one face two areas of adhesive separated by a non-adhesive area extending across substantially the whole width of the label, the adhesive areas being adapted to adhere to the package, one to each side of the line of perforations. A satisfactory method and apparatus for forming the seal and the line of perforations to provide an initial tamper-evident tear-off strip is not disclosed.
Heretofore, no system has been devised for forming a reclosable tamper-proof seal which can be economically applied for safe-guarding the contents of the bag prior to its being opened by the ultimate consumer.